scrolling to top of a TabView child feature using ScrollViewProxy

[majelbstoat]

I have a pretty classic TabView navigation, where I'd like a second tap on a tab to pop to the root of the feature, and a third tap to scroll to the top of the view. I'm currently using the provided sending method to create the selection binding:

TabView(selection: $store.selectedTab.sending(\.tabSelected), content: {
  QuestionsView().tag(Tag.questions)
  OtherView().tag(Tag.other)
}

which works great to switch between tabs. I have a tabSelected action in my reducer which sets the desired state:

            case let .tabSelected(tab):
                if state.selectedTab == tab {
                    if tab == .questions {
                        if state.questions.path.isEmpty {
                            // third click, scroll to top... how do I get a proxy?
                            return .run {
                              // proxy.scrollTo(ScrollAnchor.questionsTop, anchor: .bottom)
                            }
                        } else {
                            // second click, pop to root
                            state.questions.path.removeAll()
                        }
                    }
                } else {
                    // first click, switch tab
                    state.selectedTab = tab
                }
                return .none

To do scroll to top, I need a ScrollViewProxy which I can get in the view:

ScrollViewReader { proxy in 
  TabView(selection: $store.selectedTab.sending(\.tabSelected), content: {
    QuestionsView().tag(Tag.questions)
    OtherView().tag(Tag.other)
  }
}

However, I can't find an easy way to get that proxy to the reducer. I looked into rewriting or extending sending to take a proxy as a second parameter, and send that as part of the action, but it involves a fileprivate wrappedValue. (I don't even quite know if this approach would work).

Things I'm wondering:

• Is this the right way to model this kind of thing?
• Can I get a ScrollViewProxy some other way, like through a dependency?
• Controlling the child from the parent in this way feels a bit like blurring the separation of concerns a little. Is this even the expected way to handle child/parent interactions?

[majelbstoat]

I went with creating my own binding, and it works, though I admit, I'm a little hazy on whether it's a reasonable approach:

@Reducer
struct RootFeature {
    @ObservableState
    struct State {
        var selectedTab = Tab.home
        var questions = QuestionsFeature.State()
    }

    enum Action {
        case tabSelected(Tab, ScrollViewProxy)
    }

    enum Tab {
        case questions
        case other
    }

    var body: some ReducerOf<Self> {
        Reduce { state, action in
            switch action {
            case let .tabSelected(tab, proxy):
                if state.selectedTab == tab {
                    if tab == .questions {
                        if state.questions.path.isEmpty {
                            // scroll to top
                            withAnimation {
                                proxy.scrollTo(ScrollAnchor.questionTop, anchor: .bottom)
                            }
                        } else {
                            // pop to root
                            state.questions.path.removeAll()
                        }
                    }
                } else {
                    state.selectedTab = tab
                }
                return .none
            }
        }
    }
}
    
struct RootView: View {
    @State var store: StoreOf<RootFeature>

    func createTabViewBinding(proxy: ScrollViewProxy) -> Binding<RootFeature.Tab> {
        Binding(
            get: { store.state.selectedTab },
            set: { selectedTab in
                store.send(.tabSelected(selectedTab, proxy))
            }
        )
    }

    var body: some View {
        ScrollViewReader { proxy in
            TabView(selection: createTabViewBinding(proxy: proxy), content: {
                QuestionsView().tag(Tag.questions)
                OtherView().tag(Tag.other)
            }
        }
    }
}